.div {
  width: 200px;
  width: 1200px;
  background-color: green;
}

.div:after {
  content: "";
  display: table;
  clear: both;
}

#app {
  color: aqua;
  font-size: 30px;
}

a {
  color: black;
}

a:hover {
  color: blue;
  font-size: 77px;
}
